Multiple pin connector having ferrite core stacked capacitor filter



J. J. WALSH MULTIPLE PIN CONNECTOR HAVING FERRITE CORE STACKED CAPACITORFILTER Original Filed Sept. 12, 1966 Nov. 3, 1970 I: 1 kw ATTORNEYUnited States Patent 3,538,464 MULTIPLE PIN CONNECTOR HAVING FERRITECORE STACKED CAPACITOR FILTER James J. Walsh, Erie, Pa., assignor toErie Technological Products, Inc., Erie, Pa., a corporation ofPennsylvania Continuation-impart of applications Ser. No. 306,406 andSer. No. 306,407, both filed Aug. 20, 1963, now Patent Nos. 3,275,954and 3,275,953, which is a continuation of applications Ser. No. 578,577,Sept. 12, 1966, and Ser. No. 805,099, Feb. 18, 1969, both now abandoned.This application Oct. 13, 1969, Ser. No.

Int. Cl. H01h 7/14; H01g /01 US. Cl. 333-79 12 Claims ABSTRACT OF THEDISCLOSURE This application is a continuation in part of applicationsSer. No. 306,406 and Ser. No. 306,407, now Pats. 3,275,954 and 3,275,953and a continuation of applications Ser. No. 578,577, filed Sept. 12,1966, abandoned, and Ser. No. 805,099, filed Feb. 18, 1969, nowabandoned.

This invention improves the combined connector and filter assembly bysandwiching a multiple capacitor laminate or monolith between the partsof the connector housing. This permits a reduction in size due to thecompact construction provided by the laminate. In a preferred form,there are several capacitor laminates alternating with ferrite plates toprovide a filter of the desired number of stages.

In the drawing, FIG. 1 is an elevation of a connector, partly brokenaway, FIG. 2 is an exploded view of one of the capacitor laminates usedin the connector, and FIG. 3 is a section through a preferred form offilter having a ferrite plate sandwiched between two capacitorlaminates.

The connector shown in FIG. 1 has a plurality of pins, each representinga circuit. The male connector is shown in FIG. 1. The female counterpartis of conventional design. The term pin is used to designate either amale or a female connector.

The connector has a metallic housing 1 suitably supporting members 2 and3- of insulating material bolted or otherwise fastened together. Themembers 2, 3 have aligned sockets 4, 5 each associated with a pin 6. Inthe bottoms 7, 8 of the sockets are aligned clearance openings 9, 10which provide clearance so the pins can float to facilitate insertionand removal. The pins are provided with thrust collars 11, 12respectively larger than the openings 9, 10. The collar '11 may beintegral with the pin 6 and the collar 12 may be suitably fastened tothe pm.

In order to reduce radio frequency interference, there is sandwichedbetween the parts 2 and 3 a filter assembly comprising upper and lowermultiple capacitor laminates 13, 14 and an intermediate ferrite plate 15held together by the peripheral metal band 16 which serves as the groundterminal for the filter assembly and is usually electrically connected(for example, by spring contact 116a) to the metallic housing 1.

3,538,464 Patented Nov. 3, 1970 "ice In a preferred form, the multiplecapacitor laminates 13 and 14 are of similar construction and comprise aplurality of films of green ceramic from 2-3 mils thick suitablyelectroded and stacked one on top of the other and fired into a unitaryceramic body in which the films coalesce to form a sealed unitarystructure. The dielectric films are too thin to be illustrated in FIG. 1and are, accordingly, illustrated in FIGS. 2 and 3.

The particular multiple capacitor laminate shown in FIGS. 2 and 3comprises four films 17, 18, 19, 20, although obviously a differentnumber of films could be used. As will be explained hereafter, film 18carries a ground electrode and films 17 and 19 carry live electrodes incapacity relation to the ground electrode. Less capacity may be obtainedby omitting the film 17. More capacity may be obtained by adding anotherfilm 18 below the film 17 or by further stacking in alternating relationadditional films carrying ground and live electrodes in accordance withthe principles of multiple electrode capacitors. These films are made ofsuitable dielectric ceramic, for example, one of the titanates, and havea thickness of from 2-3 mils, although thicker films may be used forhigher voltage applications. The film 117 has on its upper surface aplurality of metal paint live electrodes 21, each extending to the edgeof a hole 22 in alignment with the pin 6 and spaced from each other soas to be electrically separate. Between adjacent electrodes 21 is a gridelectrode 23 which is spaced from the electrodes 21. The grid electrode23 extends to the outer edge of the film 17. The purpose of the gridelectrode 23 is to provide a ground potential between adjacentelectrodes 21 to eliminate cross-coupling between adjacent electrodes.The electrode 23 may be omitted if its function is not desired. The film19 is a duplicate of film 17 and corresponding parts are indicated bythe same reference numerals. The film 18 has on its upper surface ametal paint ground electrode 24 extending over the entire upper surfaceexcept for margins 25 about holes 26 which register with the holes 22 inthe films 17 and 19. Each of the electrodes 21 of the films 17 and 19(the live electrodes) is in capacity relation to the ground electrode 24of the film 18. The film 20 has on its upper surface a plurality ofmetallized coatings 27, each encircling one of the holes 28 whichregister with the holes 22 and 26 in the other films. The purpose of thecoatings 27 is for making electrical connection to the pins and to thelive electrodes 21, for example, by flexible conductive rubber sleeves29 or other connection. Around the periphery of the film 20 is ametallized border 30 by which a soldered connection 31 may be made to aflange 32 on the metal band or ground terminal 16.

In the manufacture of the multiple capacitor laminate, the electrodes21, 23, 24 are applied to the green ceramic in the form of a hightemperature metal paint such as platinum, palladium, etc. and the filmsare stacked one on top of the other with the holes 22, 26, 28 inregister and fired. During firing, the ceramic films coalesce into aunitary ceramic structure or monolith. After the firing, the metallizedcoatings 27 and 30* may be applied in the form of a silver paint. Asilver paint coating 33' may also be applied to the bores of the holes22, 26 and 28 and another silver paint coating 34 may be applied to theperipheral edge of the laminate. The silver paint coatings are cured inan oven. The silver paint coating 33 connects the live electrodes 21 inparallel. The silver paint coating 34 connects the ground electrodes 23and 24 in parallel.

After firing and applying the silver paint coatings 27, 33 and 34, themultiple capacitor laminate is a compact sealed structure having holesaligned with the pins 6. The multiple capacitor laminate has somefiltering effect to reduce radio frequency interference. When so used,the

coating 34 is the ground terminal and the coatings 33 are the liveterminals of the filter. To improve the filtering effect, an inductivemeans such as a lossy ferrite plate is sandwiched between the twomultiple capacitor laminates 13, 14 and the assembly is held together byground terminal 16. The ferrite plate has holes 35 in alignment with theholes in the laminate. The unitary ferrite plate 15- is a convenientconstruction. It may be replaced by several smaller ferrite plates or byindividual ferrite beads telescoped over the pins 6. The active part ofthe ferrite is the section encircling each pin having an areacorresponding to that of a bead.

What is claimed is:

1. A connector, a multiple capacitor filter unit comprising a laminateof a plurality of ceramic dielectric films coalesced into a unitarystructure and having a plurality of holes speced from each other andextending through the films of the laminate in the thickness direction,live and ground electrode means on and in capacity relation to eachother through films of the laminate, the ground electrode means beingmargined from the holes and extending to the peripheral edge of thelaminate, the live electrode means having a plurality of separateportions electrically insulated from each other respectively extendingto the edges of separate holes to provide a plurality of separatecapacitors, a conductive coating overlying and encircling the peripheraledge of the laminate and connected to said ground electrode means,conductive coatings overlying the edges of the holes and connected tothe respective live electrode means, means of insulating providingsockets on opposite sides of said laminate and aligned with said holes,a pin extending through each hole and through the associated sockets, anelectrical connection from each pin to the conductive coating overlyingthe edges of the hole through which the pin extends, and an electricalconnection to the conductive coating overlying and encircling theperipheral edge of the laminate.

2. The connector of claim 1 in which the filter unit comprises twolaminates of similar construction, the laminates being spaced from eachother with aligned holes, and inductive means in the space between thelaminate having holes through which the respective pins extend, saidinductive means having separate active portions encircling therespective pins.

3. The connector of claim 2 in which the inductive means comprisesferrite beads telescoped over the pins.

4. The connector of claim 2 in which the sockets and holes provideclearance around the pins so the pins can tfloat to facilitate insertionand removal.

5. The connector of claim 4 in which the electrical connection from oneof the pins to its live electrode is a flexible conductive rubbersleeve.

6. A multiple feed through filter comprising a first laminate having aplurality of ceramic dielectric films coalesced into a unitary structureand having a plurality of registering holes extending through the filmsof the laminate in the thickness direction, and ground and liveelectrode means on and in capacity relation to each other through filmsof the laminate, the ground electrode means being margined from theholes and extending to the peripheral edge of the laminate, the liveelectrode means having a plurality of separate portions electricallyinsulated from each other respectively extending to the edges ofseparate holes to provide a plurality of separate capacitors, aconductive coating overlying and encircling the peripheral edge of thelaminate and connected to said ground electrode means, conductivecoatings overlying the edges of the holes and connected to therespective portions of the live electrode means, a second laminatespaced from the first laminate having a plurality of ceramic filmscoalesced into a unitary structure, a plurality of holes spaced fromeach other and extending through the second laminate in the thicknessdirection, and live and ground electrode means on and in capacityrelation to each other through films of the laminate, the groundelectrode means of the second laminate being margined from the holes andextending to the peripheral edge of the second laminate, the liveelectrode means of the second laminate having a plurality of separateportions electrically insulated from each other respectively extendingto the edges of separate holes to provide a plurality of separatecapacitors, a conductive coating overlying and encircling the peripheraledge of the second laminate and connected to its ground electrode means,conductive coatings overlying the edges of the holes of the secondlaminate and connected to the respective portions of its live electrodemeans, the holes of the second laminate registering with the holes inthe first laminate, a plurality of conductors each extending through aseparate hole in the first laminate and the registering hole in thesecond laminate and each connected to the conductive coatings on theregistering holes through which it extends, inductive means in the spacebetween the laminates having a plurality of active portions eachsurrounding one of the conductors, and a metal band holding thelaminates together and connecting said ground electrode means.

7. The filter of claim 6 in which the inductive means comprises ferritebeads telescoped over the lead wires.

'8. A filter device including an integral capacitive device comprising aunitary ceramic dielectric monolith containing therein is superimposedrelationship a first set of parallel capacitor ground electrodesextending in substantially planar form from exterior border to exteriorborder of the monolith and generally parallel each to others thereof andeach such ground electrode having a plurality of areal voids therein,and said monolith and generally parallel each to others thereof and eachsuch ground electrode having a plurality of areal voids therein, andsaid monolith further containing therein a second set of smallercapacitor elecerodes disposed in parallel relation between electrodes ofaid first set but insulated therefrom by respective thin portions ofsaid monolith, and there being between two electrodes of said first setat least two substantially coplanar electrodes of said second set eachinsulated from the other by said monolith, and a plurality of terminalconductors each extending through aligned ones of the areal voids insaid electrodes of the first set and each insulated from the other andfrom said electrodes of said first set and electrically contactingaligned parallel electrodes of a respective group of electrodescomprised in the said set of smaller electrodes, and means electricallyinter-connecting the electrodes of said first set, whereby said monolithcontains a plurality of capacitors having a common ground connection andrespective other individual terminals, all disposed in a compact spatialarrangement.

9. A filter device according to claim 8, in which guardcircuit conductormeans are contained in said monolith disposed in coplanar relationshipwith respective ones of the electrodes of said second set and encirclingand shielding each such electrode from all others thereof and insulatedby said monolith from all of said electrodes of said second set ofelectrodes and from said terminal conductors, said guard-circuitconductor means being electrically connected to the electrodes of saidfirst set.

10. A method of producing a multiple-unit integral capacitive devicecomposed essentially of a monolithic dielectric structure containing aplurality of capacitor units each comprising a plurality of superimposedparallel electrodes of first and second sets thereof, and terminalconductors, said method including the steps of:

forming a plurality of thin rectangular wafer-like sheets of dielectricceramic greenware;

disposing on one face of each of a first set of said sheets a patternedcoat of adherent conductive material extending from border to borderthereon but having spaced-apart small areal voids to provide thereonthin capacitor electrodes with spaced areal voids;

disposing on one face of each of a second set of said sheets an array ofspaced-apart thin coats of adherent conductive material to provide oneach sheet of said second set an array of capacitor electrodes smallerthan those on said first set of sheets, and each electrode of said arraybeing areally disposed to register with a respective one of said arealvoids when sheets of said first and second sets are superimposed inalternation in a stack;

stacking said first and second sets of sheets in superimposedrelationship with coated faces of all of the sheets facing the samedirection;

forming holes transversely through the monolithic structure so each holeextends through a middle portion only of each of a respective set ofsuperimposed voids of said first set of sheets;

firing the unitary structure to form a dense rigid monolithic structure;and

applying conductive material over the interior surfaces bounding saidholes whereby to electrically interconnect the respective electrodes ofsaid second set of sheets, and separating interconnecting said thincapacitor electrodes.

11. A method as defined in claim 10, including the step of applying athin conductive stripe between nextadjacent electrodes on the face ofeach of said second set of ceramic sheets, and electrically connectingthe said stripes to the electrodes on said first set of ceramic sheets,whereby to provide a guard means electrostatically isolatingnext-adjacent ones of the smaller electrodes each from the other.

12. A method as defined in claim 10, including the step of mounting saidmonolith on a metal bulkhead and electrically connecting said thincapacitor electrodes to said bulkhead.

References Cited UNITED STATES PATENTS 3,160,790 12/1964 Mittler 174-6853,275,953 9/1966 Coda et a1. 333-79 3,379,943 4/1968 Breedlove 3l726l X3,426,257 2/1969 Youngquist 3l7-256 HERMAN K. SAALBACH, Primary ExaminerT. J. VEZEAV, Assistant Examiner U.S. c1. X.R. 317---256 g

